Case-1: When logging in to the dialer and there are no voice prompt when you click on the call agent phone, make sure you have provided OB Support or Chat support your IP Address. This is to add your IP Address to the server allowing you to take in calls.
Case-2: When logging in to the dialer, and zoiper has an error. Make sure before you logged in into the campaign, your zoiper has been configured to the campaign by IT Department. Every time you get a new campaign that will be using the OB Dialer, you will have to configure zoiper. This is a one time thing for each campaign.
If issue still occur kindly do the basic trouble shooting. Reset modem and PC or laptop but still after rebooting nothing changed, please contact technical support, OB Support or Chat support.